Efeito da adição de carboneto de silício em pó na geração de microtrincas e na topografia da superfície na usinada por descargas elétricas do aço-rápido ABNT M2

Abstract

This work investigates surface topography and microcrack generated by electrical discharge machining in workpieces of high speed steel (ABNT M2). Three different commercial dielectric fluids are used with and without addition of silicon carbide powder. Electrodes of electrolytic copper are used in roughing operations. The microcracks are evaluated using SEM analysis by two parameters: density and length. Surface finishing is measured by the average roughness parameter (Ra) and surface topography with studied within SEM. In general, the samples machined with the addition of powder of SiC presented significant improvements in the surface finishing, compared to samples machined by conventional EDM. It was observed that addition of SiC powder has no effect in the length of the microcracks. However, it affected microcrack density. The results suggest that the powder penetrates into the gap between the tool and the workpiece, resulting in more uniform and directed sparks.